Conventional jack is made by fixing a hydraulic pump and a hydraulic cylinder into a base of cast iron, which however has the following defects:
1. It is easy to produce holes in the casting base so that the holes may easily break the casting.
2. During the drilling processing for hydraulic oil conduit, the scrap or dust of casting may carry static electricity to adhere on the conduit wall which may scratch the sealing ring and cause leakage of hydraulic system of the jack.
3. When drilling the hydraulic holes either horizontal or vertical hole, it takes longer time for drilling such holes and it still requires the welding procedure to blind the unnecessary hole.
4. The casting is fragile and is easily broken or damaged during handling and uses.
5. Whenever drilling the holes, it may waste the casting material if the drilling precision is not allowed.
6. The check valves provided in the hydraulic oil passage is processed within the casting base in a difficult way since such a "piping system" can not be installed outside the casting base.
The present inventor has found the defects of conventional jack and invented the molding jack base.